Method of acquiring ghost-free signatures for broadband source calibration

Patent metadata

Field	Value
Publication number	US-2016109601-A1
Application number	US-201414585468-A
Country	US
Kind code	A1
Filing date	Dec 30, 2014
Priority date	Oct 20, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

Embodiments described herein provide a method for acquiring de-ghosted data that can be utilized for calibration of a seismic source (air gun) model. Positions of a plurality of seismic receivers can be determined to enable efficient removal of an interference effect of ghost signals originating from mirrored versions of at least one seismic source that are received at the plurality of seismic receivers (hydrophones). Data (de-ghosted or near de-ghosted) can be acquired from the plurality of seismic receivers located at the determined positions by operating the at least one seismic source. A calibrated model of the at least one seismic source can be prepared based on the acquired (de-ghosted) data.

First claim

1 . A method, comprising:
determining positions of a plurality of seismic receivers to enable removal of an interference effect of ghost signals originating from mirrored versions of at least one seismic source that are received at the plurality of seismic receivers; acquiring data from the plurality of seismic receivers located at the determined positions by operating the at least one seismic source; and preparing a calibrated model of the at least one seismic source based on the acquired data.

2 . The method of claim 1 , wherein determining the positions of the plurality of seismic receivers comprises:
adjusting predicted positions of the plurality of seismic receivers in an iterative manner such that differences in travel times between arrivals at the plurality of receivers of direct signals from the at least one seismic source and arrivals at the plurality of receivers of the ghost signals from the mirrored versions of the at least one seismic source result in complementary ghost wave functions.

3 . The method of claim 1 , wherein determining the positions of the plurality of seismic receivers comprises maximizing a cost function.

4 . The method of claim 3 , wherein the cost function is related to an envelope function of frequency domain amplitude responses of ghost wave functions associated with predicted positions of the plurality of seismic receivers for a specific position of the at least one seismic source.

5 . The method of claim 3 , wherein the cost function is given by:

C
=

min
ω



(

max

1
≤
j
≤
N





1
-



r
j





g
j







-
ω





g
j



-



r
j



v



)

,

wherein r j is a vector from a position of the at least one seismic source to a predicted position of one of the plurality of seismic receivers, g j is a vector from a position of a mirrored version of the at least one seismic source to the predicted position of the seismic receiver, ω is an angular frequency, v is an average acoustic wave propagation velocity, N is a number of the plurality of seismic receivers and j=1,2, . . . , N.

6 . The method of claim 1 , wherein determining the positions of the plurality of seismic receivers to enable removal of the interference effect comprises:
selecting initial positions of the plurality of seismic receivers; and converging from the initial positions to the determined positions of the plurality of seismic receivers to enable removal of the interference effect.

7 . The method of claim 1 , wherein acquiring the data comprises:
measuring the data by performing a plurality of energy emissions from the at least one seismic source.

8 . The method of claim 7 , wherein the plurality of energy emissions comprise at least 20 shots from the at least one seismic source.

9 . The method of claim 1 , wherein the plurality of seismic receivers located at the determined positions have an identical horizontal distance from the at least one seismic source, the horizontal distance comprises a trajectory parallel to a plane tangent to a spherical surface approximating a sea surface, the at least one seismic source and the plurality of seismic receivers being located below the sea surface.

10 . The method of claim 1 , wherein the plurality of seismic receivers located at the determined positions are positioned around the at least one seismic source.

11 . The method of claim 1 , wherein determining the positions of the plurality of seismic receivers comprises:
finding an angular frequency of the data that minimizes a value of an envelope function of frequency domain amplitude responses of ghost wave functions associated with the positions of the plurality of seismic receivers.

12 . The method of claim 1 , wherein the plurality of seismic receivers comprise at least three seismic receivers.

13 . The method of claim 1 , wherein the positions of the plurality of seismic receivers are determined for a specific position of the at least one seismic source.

14 . A non-transitory machine-readable medium storing instructions executable by a processing resource to cause a machine to:
determine positions of a plurality of seismic receivers to enable removal of an interference effect of ghost signals originating from mirrored versions of at least one seismic source that are received at the plurality of seismic receivers; acquire data from the plurality of seismic receivers located at the determined positions by operating the at least one seismic source; and prepare a calibrated model of the at least one seismic source based on the acquired data.

15 . The machine-readable medium of claim 14 , wherein the instructions executable by the processing resource further cause the machine to:
determine the positions of the plurality of seismic receivers based on maximizing a cost function.

16 . The machine-readable medium of claim 15 , wherein the

Assignees

• Pgs Geophysical As

Inventors

• Wisløff Jens Fredrik Barra
• Barker Daniel

Classifications

• G01V2210/56

  De-ghosting; Reverberation compensation · CPC title

• G01V1/364

  Seismic filtering (G01V1/37 takes precedence) · CPC title

• G01V1/3817 Primary

  Positioning of seismic devices · CPC title

• G01V1/28 Primary

  Processing seismic data, e.g. for interpretation or for event detection (G01V1/48 takes precedence) · CPC title

• G01V1/36

  Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy · CPC title